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A method is described for calculating the seismic response of an arbitrarily shaped interface below a homogeneous medium by the Kirchhoff integral in the time domain. It is shown, by comparison with other numerical techniques, that this method yields accurate results for reflections. The errors in calculating diffractions are tolerable if the distance of the receiver from the shadow boundary of reflection is not too large; this is usually the case in horizontal seismic profiling. The method has been applied to model qualitatively some typical features in record sections of the deep seismic reflection profile DEKORP2-S. This profile is characterized by numerous strongly curved events that are concentrated mainly in two areas of the profile. These signals can be addressed as diffractions from an interpretation of the travel times. Dynamic calculations, however, show that the surprisingly high amplitudes cannot be explained by diffracting elements like fault edges or small-scale inhomogeneities; instead, one has to assume cylindrically or spherically curved reflectors with a radius of at least 4 km. Some possible geological explanations for these structures, like diapiric intrusions or antiformal stacks, are discussed in view of the tectonic evolution of the Central European Variscides.
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